The present invention relates to a lane-keep control system which controls the vehicle so as to travel within a target lane.
Japanese Patent Provisional Publication No. 2001-310719 discloses a lane-keep control system which is arranged to prevent a host-vehicle from deviating from a traveling lane by controlling a driving/braking force when there is a deviation tendency of the host-vehicle from the traveling lane.
However, this system is required to ensure a further smooth operation fitted with a driver""s feeling even if a direction of a yawing moment due to steering operation is the same as that of a yawing moment due to the driving/braking force control.
It is therefore an object of the present invention to provide an improved lane-keep control system which prevents a host-vehicle from deviating from a traveling lane by controlling a driving/braking force so as not to apply a strange feeling to a driver even if a direction of a yawing moment due to steering operation is the same as that of a yawing moment due to a driving/braking force control for a lane-keep control.
An aspect of the present invention resides in a lane-keep control system which is for a host-vehicle and comprises a control unit. The control unit is configured to detect a traveling condition of the host-vehicle, to determine that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition, to calculate a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when there is the tendency of the lane deviation, to detect a steering state quantity indicative of a quantity of state of a steering wheel, to correct the driving/braking force controlled variable on the basis of the steering state quantity, and to control a driving/braking force of each wheel according to the driving/braking force controlled variable.
Another aspect of the present invention resides in a lane-keep control system of a host-vehicle which system comprises a traveling condition detecting device that detects a traveling condition including a state of a steering wheel of the host-vehicle; a brake hydraulic pressure control circuit that independently controls a hydraulic pressure of each wheel cylinder of the host-vehicle to generate a desired braking force of the host-vehicle; a driving torque control unit that controls a driving torque applied to driving wheels of the host-vehicle; and a driving/braking force control unit coupled to the traveling condition detecting device, the brake hydraulic control circuit and the driving torque control unit. The driving/braking force control unit is arranged to determine that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition, to calculate a target yawing moment reference value on the basis of the traveling condition when there is the tendency of the lane deviation, to calculate a target yawing moment by correcting the target yawing moment reference value according to a rate of change of the state of the steering wheel with respect to time, to calculate a target brake hydraulic pressure according to the traveling condition and the target yawing moment, to calculate a target driving force according to the traveling condition and the target brake hydraulic pressure, and to output a first drive signal indicative of the target brake hydraulic pressure to the brake hydraulic pressure control circuit and a second drive signal indicative of the target driving force to the driving force control unit.
A further another aspect of the present invention resides in a method of executing a lane-keep control of a host-vehicle. The method comprises a step for detecting a traveling condition of the host-vehicle; a step for determining that there is a tendency of a lane deviation that the host-vehicle is deviating from a traveling lane, on the basis of the traveling condition; a step for calculating a driving/braking force controlled variable of each wheel according to the traveling condition so as to generate a yawing moment directed toward a direction of preventing the lane deviation when there is the tendency of the lane deviation; a step of detecting a steering state quantity indicative of a quantity of state of a steering wheel; a step of correcting the driving/braking force controlled variable on the basis of the steering state quantity; and a step of controlling a driving/braking force of each wheel according to the driving/braking force controlled variable.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.